1. Field of the Invention
The present invention relates to a material for the purification of fluids. More particularly, the present invention relates to a material for flocculating and separating organic substances or surface active agents contained in waste water.
2. Description of the Prior Art
Presently, one of the most widely used treatments for waste water containing organic substances is an activated sludge process. According to the activated sludge process, micro-organisms such as bacteria are propagated, organic substances in the sludge are adsorbed in the micro-organisms and the impurities are sedimented and separated. This process exerts a very high purifying capacity. Treated water according to the activated sludge process can be directly discharged into rivers and the like as long as certain water quality regulation are met.
In the conventional activated sludge process, if waste water containing corruptible organic substances such as animal oils is treated, the quality of treated water satisfies the standard value, but the quality of treated water is not so sufficient that treated water is completely harmless to a natural water zone, because the pH value is in the acidic region, each of BOD and COD is about 30 to about 80 ppm and the smell is not completely removed. Moreover, this treated water cannot be suitably used as industrial water or washing water. Moreover, if an activated sludge tank is maintained at a temperature of 20.degree. to 30.degree. C. suitable for propagation of micro-organisms, aeration is always necessary for supply of oxygen and other conditions should be set, and a long time is necessary for completion of the treatment and complicated equipment is necessary. Accordingly, the equipment cost is large, and a large maintenance fee and a great deal of labor are necessary.
As the flocculating agent for flocculating organic substances and the like contained in waste water, there can be mentioned alumina sulfate, poly(aluminum) chloride and ferric chloride. In addition, calcium phosphate derived from an animal bone powder has been used as an active calcium agent or flocculating agent.
Calcium phosphate derived from animal bone powder, as well as various other additives such as preservative agents for inhibiting the growth of micro-organisms, and anti-oxidants for preventing deterioration by oxidation, have been used for maintaining freshness in fluids and foods and attaining a preservative effect. For example, as the preservative agent for foods, there can be mentioned food additives such as not only benzoic acid, sorbic acid and propionic acid, but also a sheet or bag formed by sandwiching a powder of active carbon having a fungicidal action to bacteria with a synthetic resin film, paper or woven sheet and a paper impregnated with water containing active carbon. As the anti-oxidant, there can be mentioned food additives such as not only ascorbic acid and erysorbic acid but also a bag having an active carbon powder sealed therein.
Active carbon having an adsorbing action, tertiary iron oxide and ceramics can be used for filtering and deodorizing an aqueous solution and/or air containing impurities and organic substances.
The above-mentioned additives have an effect of preserving fluids and foods, but they also have a risk of jeopardizing the safety of the human body. Some additives can even have harmful actions such as carcinogenic and teratogenic actions. In addition, active carbon and a bag having active carbon sealed therein are poor in the preservative effect or oxidation-preventive effect.
Active carbon and tertiary iron oxide exert a filtering action as the adsorbent, but the life is short and regeneration after the application, or repeated use, is impossible. Since ceramics are inorganic substances, they do not react with organic substances, and accordingly, they do not function sufficiently as the filtering material.
As a means for obviating the above-mentioned disadvantages, there have been proposed various processes in which calcium phosphate derived from an animal bone powder is used as an active calcium agent or flocculating agent. Calcium phosphate has also been used in various fields for antiseptic and flavor-improving additives, acid neutralizers, dechlorinating agents for service water and flocculating agents for organic waste waters (see Japanese Patent Publications No. 53816/84 and No. 6365/81 and Japanese Patent Application Laid-Open Specifications No. 5309/81, No. 231965/86 and No. 4490/87). All of the above-mentioned documents are incorporated herein by reference as if the entire contents thereof were fully set forth herein.
According to these known processes, however, calcium phosphate additives are prepared only by calcining an animal bone to remove the majority of organic substances and carbon by combustion, or only by boiling or steaming an animal bone to remove the majority of organic substances and carbon. Accordingly, removal of carbon or sulfides is insufficient, and these processes are defective in that high-quality products cannot be obtained.